1. Field of the Invention
The present invention relates to a bowl-type vibratory finishing machine employing an extremely simple yet highly effective arrangement of components which enable a relatively low-energy-input drive system to efficiently impart an extraordinarily aggressive finishing action to a mixture of workpieces and finishing media contained within the finishing chamber of a movably supported bowl.
2. Prior Art
Two basic types of eccentric-driven vibratory finishing machines are in common use. One type employs an elongate receptacle which defines an elongate, trough-like finishing chamber extending in a substantially horizontal plane, and which is vibrated by rotating one or more eccentrically-weighted drive shafts about one or more substantially horizontal axes extending along the receptacle. This first type of machine is known in the art as a "tub-type machine" or simply a "tub machine," and its receptacle is commonly called a "tub." Another type uses a substantially toroidal-shaped receptacle which defines an annular, trough-like finishing chamber extending in a generally horizontal plane, and which is vibrated by rotating an eccentrically-weighted drive shaft about a substantially vertical "center axis" located centrally of the receptacle when the receptacle is at rest. This latter type of machine is known in the art as a "bowl-type machine" or simply a "bowl machine," and its receptacle is commonly called a "bowl." The present invention relates to bowl machines.
During the operation of a bowl machine, the bowl vibrates in a complex gyratory type of motion which subjects the bowl's contents to impulses that include components which extend axially, radially and circumferentially with respect to the center axis of the machine. The impulses are oriented and timed to effect both circumferential precession and rotary churning to effect a finishing action. Surface finishing operations such as deburring, burnishing, descaling, cleaning and the like may be performed depending on the type of vibratory action which is provided, the type of finishing media employed, and other factors.
An objective in designing a bowl machine is to provide a simple and relatively inexpensive, yet reliable system which will enable a truly aggressive finishing action to be imparted to the contents of the bowl. A challenge facing the industry has been to provide an efficient bowl machine design which is capable of generating the type of large amplitude vibrations needed to provide an aggressive finishing action, while minimizing the use of inordinately massive and costly components. An arrangement of bowl machine components which permits a truly aggressive finishing action to be achieved with genuine efficiency using a low-energy-input drive system has long eluded the experts of this industry.
Those skilled in the art have maintained different and conflicting theories on where the nodal point about which the bowl gyrates optimally should be located along the center axis. Some maintain that the nodal point should be located within or near a horizontal plane which includes the center of gravity of the bowl's contents in an effort to minimize horizontal impulse components imparted to the bowl's contents and to maximize vertical impulse components. Others maintain that a nodal point location slightly below the bottom of the bowl is desirable since it gives something of a mix of vertical, horizontal and circumferential impulse components. Still others advocate higher and lower nodal point locations. A practical problem not well addressed by these conflicting proposals is that, in reality, with most bowl machine designs there is a tendency for the location of the nodal point about which the bowl gyrates to move about quite extensively (i.e., to shift about in a very undesirable manner) during start-up and shut-down of the machine, and during operation in response to changes in the loading of the bowl. If the location of the nodal point is displaced to any significant degree from the nodal point location for which the machine was designed, the machine operates inefficiently, if at all, and subjects its drive and suspension system components to needless wear.
Those skilled in the art have similarly advanced difference and conflicting theories regarding design approaches which should be followed to determine the structural arrangement of such components as the bowl and its suspension system, the locations and types of eccentric weights which are carried on the drive shaft to vibrate the bowl, the type of power-operated drive which should be used to rotate the eccentric drive shaft, and the character and location of the connection made between the power-operated drive and the drive shaft.
Considerations such as nodal point location, the number, location and arrangement of eccentrics, and others of the foregoing design factors are rendered more complex inasmuch as they cannot be analyzed and treated independently; these important considerations are interrelated and interact to influence and determine such other factors as:
(a) the complexity and cost of manufacture of the machine; PA0 (b) the ease with which the machine can be serviced and such limited-life parts as bearings replaced; PA0 (c) the longevity of service which can be expected from the machine; PA0 (d) the sensitivity of the machine to different bowl loadings, i.e. whether it can handle a wide range of large and small, as well as heavy and light loads; and, PA0 (e) the type of vibratory movement which is imparted to the bowl, which, in turn, determines such things as:
(i) the type of churning movement which will be executed by a mixture of media and workpieces in the bowl; PA1 (ii) the direction and rate of precession of the mixture; and, PA1 (iii) the efficiency and aggressiveness of the resulting finishing action in terms of the amount of energy which must be expended and the time required to execute a desired finishing operation.
With so many interrelated and interacting variables to consider, it is no wonder that much of the progress which has been made in improving bowl machine designs has resulted not from the promulgation of desk-side calculations, but rather through the building, testing, rebuilding and continued modification of prototype machinery. Once a machine has been rendered operable and proven through testing, the machine design has then been made the subject of attempts to understand and divine plausible theories which may explain the mysteries of its operation. Stated in another way, what has long eluded those skilled in the art is a simple and straightforward design approach which can be implemented with ease to provide a lean and relatively inexpensive bowl-type vibratory finishing machine of desired capacity having the capability to efficiently generate a highly aggressive finishing action.
3. Reference to Relevant Patents
The vibratory finishing machine art is replete with complex and conflicting theories and proposals which are intended to facilitate the design of a bowl-type vibratory finishing machine (1) that is simple and straightforward in construction, (2) that is easy to manufacture, install, use, maintain and repair, and (3) which incorporates the elusive capability to efficiently impart a truly aggressive finishing action utilizing a low-energy-input drive system. The disclosures of the following patents are incorporated herein by reference inasmuch as their introductory discussions present, by way of examples, some of the conflicting theories and proposals which typify the very genuine frustrations which have long stood as stumbling blocks to those skilled in the art:
BOWL-TYPE VIBRATORY FINISHING MACHINE, U.S. Pat. No. 4,301,625 issued Nov. 24, 1981 as a continuation-in-part of UNLOADING SYSTEM FOR BOWL-TYPE VIBRATORY FINISHING MACHINE, U.S. Pat. No. 4,184,290 issued Jan. 22, 1980 to John F. Rampe as a continuation-in-part of BOWL-TYPE VIBRATORY FINISHING MACHINE, U.S. Pat. No. 4,091,575 issued May 30, 1978 to John F. Rampe; and,
SUSPENSION SYSTEM FOR BOWL-TYPE VIBRATORY FINISHING MACHINE, U.S. Pat. No. 4,090,332 issued May 23, 1978 to John F. Rampe as a continuation-in-part of BOWL-TYPE VIBRATORY FINISHING MACHINE, U.S. Pat. No. 4,091,575 issued May 30, 1978 to John F. Rampe. The disclosures of the foregoing patents are also incorporated for their teachings of bowl machine charging and discharging devices as well as other bowl machine features which, although they form no part of the present invention, are nonetheless usable with bowl machines that embody features of the present invention.